If Heterodying is the Spirit of Theremin Then…

And now folks -

The ultimate challenge.. Give this a few tubes and turn it into a self-playing classic theremin!

;-)

Just got a message from the pope in Rome: Roman catholic theremin players are not longer allowed to reach the zero beat zone of their instruments, because that would turn heterodyning into homodyning (two oscillators of identical frequency interacting)...

That video above of what dew and Fred have been working on is really impressive because it eliminates the Thereminist, which may not be a bad idea. 0-:

Hetero-dying is what this thread is titled, that is what’s happening when someone takes the vow of poverty and enters into the life of servitude. Homo-dinning is what the evening gathering for dinner eventually becomes. (-‘

To be on topic about heterodyning my thinking from something Fred mentioned about mixing and getting a sine wave result made me think that I actually need to convert the TTL output of the crystal oscillator to a good HF ramp wave to mix. When I used the solid-state sine wave it makes sense to me now that it would strip out all the even harmonics as it did not have any to offer. I never know anything until I hard wire to test the results. It must remain simple in design/cost or what I am doing currently with the second tube/valve is the right approach.

Christopher

Really? Is it my right almost deaf ear that is not hearing correctly, or even the machine is not even on pitch?

If the machine is indeed off pitch, your statement of "eliminating the Thereminist would not be a bad idea" is pretty much moot point. I would enjoy the usual off pitchness of a Thereminist with a sense of musicality rather than a more precise yet robotic playing of a machine any day.

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That video above of what dew and Fred have been working on is really impressive because it eliminates the Thereminist, which may not be a bad idea. 

Christopher

In case anyone didnt realise I was joking ... ;-)

I think the "machine" does a good job of simulating 50%(+) of the "real" theremin sound we are most used to hearing, simply because its utterly out of tune! ;-) .. Give it the "right" sound, and your there! A "Classic" theremin!  (with wanne-be modern "thereminist" ;-)

No - it DOESNT eliminate the "thereminist" - It "eliminates" those who think they can play the theremin well enough to make bearable music, but actually cant!

Why is it so easy to tell when a keyboard with portamento is playing, and one isnt hearing a theremin? - Well, IMO, one often doesnt even need to listen to the sound being produced.. the notes glide at a mathematically precise rate and curve to their intended next note perfectly, and land on that note perfectly.. No thereminist does this - Not PP, Not Amey, Not Clara.. And its good that they dont! - Because, IMO, if they did then the human expression which is such a big part of what the theremin / thereminist bring, would be gone.. But I think it might be that there some ratio of accuracy / "error" and some time "window" within which correction must be achieved and accurate pitch obtained, that good thereminist manage but less good ones dont.

Ironically, IMO, that crap machine at the top of this page in some ways perhaps comes closer to "realistic" rendition of the sort of "errors" and overshoot that real wanna-be "thereminists" make - in an exagerated form though.. But get it more accurate, and get it to produce the right sound, and I think it could possibly fool someone into believing a "real" theremin was playing more easily than any keyboard ever could.... Connect it to a keyboard, and something like that would be convincing - certainly for less discerning listeners. 

"To be on topic about heterodyning my thinking from something Fred mentioned about mixing and getting a sine wave result made me think that I actually need to convert the TTL output of the crystal oscillator to a good HF ramp wave to mix. When I used the solid-state sine wave it makes sense to me now that it would strip out all the even harmonics as it did not have any to offer. I never know anything until I hard wire to test the results. It must remain simple in design/cost or what I am doing currently with the second tube/valve is the right approach." - Christopher

Chris, I deleted that post because I felt it may be too technical - im feeling a bit sensitive about the stuff I post.. Realizing that I am often just a bore!

You have loads of lovely even harmonics in your last sample - this isnt achieved by a ramp, its achieved through mixer distortion (assymetric waveform) - even simple square pulses with unequal mark/space can give loads of both odd and even harmonics..

IMO, its really only worth "perfecting" HF waveforms IF you are using a true 4Q multiplier, as only then can you be sure that what you get out will be the result of what you put in.. Its your "distorting" mixer where its all really happening.

"Really? Is it my right almost deaf ear that is not hearing correctly, or even the machine is not even on pitch?" - Amey

LOL ;-) Amey, dont worry - its So out of tune it makes my teeth hurt!  ;-)

Fred.

"Roman catholic theremin players are not longer allowed to reach the zero beat zone of their instruments" - Thierry

As a devout RC, I am worried by this - I need to ask my priest at next confession whether Monodyning is also a sin.. Oh, I like heterodyning best of all, and have no personal inclination to homodyning - But Monodyning is kind of a touchy area....

;-)

(If Monodyning is a sin, the '91 needs to be banned - as must all single oscillator synths.. )

What an interesting day, the crystal oscillator showed up a couple of days early. So I pull the tube/valve on one of my boards and swap in this $5 budget crystal “Can” at 1 MHz. I got no spec sheet and assume these come from old surplus. I guess the 4 pin layout is a standard with one corner of the can sharp not round.

There is not even a part # on the Can just CQ with 1.000. I power it with 5 volts and I have an OMG moment. The scope shows it is a square wave and I have a 330 uh choke in series to my Altermen single diode mixer. It shows great potential out of the box but I do lose some of my dual tube fat sound but retain the audio harmonic dance that an audio spectrum analyzer will reveal.

It is a clean sound; not a cheap whistle buried in reverb so this could evolve into something more musical. Some how there is a swoosh effect in the sound when rapidly moving from note to note, needs more study.

First Sample.mp3  for the history book. This is saved so I can compare against it in the future.

Edit: Sample3.mp3  in this test sample the fixed frequency is double the variable pitch frequency. This seems to get rid of the stiff note change or swoosh between notes. Where is that haunting thump sound coming from?

I will do a thermal mismatch drift study over night, that should be interesting?

Christopher

The thermal test went south rather quickly, the crystal osc sound is lacking so here I am back to where I was five years ago.  Now that is a purty good place, in fact it is a place beyond what ever I imagined I could achieve. In my early sounds I always wondered what creates the fat sound, then what sound is musical by nature. Surely the original sound method I use is a long shot discovery for me, it is my Altermen sound changing daily in character as if it were alive. (-‘

Back to dual tube/valve basics  Altermen5.mp3  only a quick sound sample

That is direct to sound card, no acoustic development other than your speakers.

Maybe I will retire now... unless an old school engineer comes along that understands the warmth of the vacuum tube.

Christopher

"Maybe I will retire now... unless an old school engineer comes along that understands the warmth of the vacuum tube." - Christopher

I think there are quite a few engineers and experimenters who "understand" this "warmth" - And some who understand that its not the tube ALONE that imparts this..

"Surely the original sound method I use is a long shot discovery for me, it is my Altermen sound changing daily in character as if it were alive. (-‘"

There have been a couple of really nice sounds I have heard from your samples - that  sample in the other thread and your rubber bucket sample - this latest sample doesnt do it for me.. But IMO, you have "done" it, you have a 'core' that could evolve into a classic - And I dont really see this as a "long shot" - Evolution can produce amazing results through trial and elimination, and ID can produce amazing results - the difference is the time each takes - 10+ years is probably enough time for one to evolve a great sound if one has luck on ones side!

A bit of ID applied to what you have evolved, and you could be "there" quite quickly IMO... Or if you are tired of the "journey" (I would fully understand this feeling ;-) why not publish the design? That way some person who aint exhausted could perhaps take the evolution forward - Retire now, keep the design to your "chosen few", and there is a stronger possibility that in 10 years time there will be nothing to show for the 10 years you have invested.

Anyway, I will delete my last post - I dont think you want to see anyone elses ideas, I get the feeling you want your stuff to be "uncorrupted" by ideas from anyone else, be this Lev, or Bob, or us lesser engineers here at TW..

Oh, BTW - I personally have no interest in whether you publish your design or not - I see absolutely no commercial viability in producing tube theremins even if your design was wonderful.. To me, its more academic interest, and others may be interested in building DIY tube theremins.

Fred.